Abstract: In order to understand the changing law of soil enzyme activities of different root dry crops under waterlogging, the experiment takes summer maize and summer soybean as the test objects, and carries out the test tube simulation test. The experiment analyzes the effects of waterlogging stress on crop roots and soil enzyme activities, and the relationship between root dry weight and soil enzyme activities. The results show that different root crops are differently affected by waterlogging stress. The overall growth of fibrous root crops was hindered, the root dry weight decreased by 3.98%～29.41%, the invertase activity decreased by 1.06%～44.08%, the urease activity decreased by 6.21%～24.45%, the soil enzyme activity rebounded for a period of time after the end of waterlogging. Taproot crops had excessive root growth, the root dry weight increased by 1.77%～76.98%, the invertase activity decreased by 5.47%～15.65%, the urease activity decreased by 0.13%～2.95%, and the soil enzyme activity could not be recovered for a period of time after the end of waterlogging. There is a strong correlation between root dry weight, soil enzyme activity and accumulated waterlogging depth of the two root crops.